When a bone is fractured, it is often necessary to hold the fragments of the bone together to allow for correct healing. If this is not done, problems such as misalignment or poor healing can occur.
A conventional means for fixing fracture fragments is an external fixator, which typically takes the form of a steel or other material rod spanning across the fracture which is fixed to the bone fragments using pins. The rod is located outside the body, while the pins penetrate the skin and are fixed in the bone. This invasive technique involves surgery, and as such there is a risk of infection of the soft tissue or bone, and further there is a risk of complications arising from the surgery.
A further disadvantage of conventional external fixators is where the fixator spans a joint, such as the wrist or ankle. The steel or other material rod may not be articulated, thereby preventing movement of the joint.
Articulated fixators are known, but these have disadvantages as well. Alignment of the articulation with the joint can be difficult if not impossible, due to articulation of the fixator not being in the plane of the joint line axis. Known devices do not allow movement in the joint's plane of motion. For example, the position of the articulation of the fixator is dependent on the position of the pins drilled in the bone which can only be drilled in a limited number of positions. Furthermore, known articulated fixators also have the disadvantage that if the fractured joints are moved in fracture situation, this will disturb the fracture position. In particular, known devices allow for multidirectional movement, including rotation, thereby allowing the fracture position to slip.
U.S. Pat. No. 4,677,971 discloses a wrist splint for the treatment of soft tissue injuries, as a splint after surgery or in fracture treatment of small bones of the wrist (carpal bones). However, the device does not have a bracelet comprising a plurality of elements arranged in a plurality of rows according to the present invention. Furthermore, as with other known devices, the device in U.S. Pat. No. 4,677,971 is not suitable for treating long bone fractures because the articulation piece is not at the fracture site or joint level and does not allow movement in the joint plane. The disclosure in WO 2006/120482, as incorporated herein by reference, also relates to a fixator or a splint.
In certain locations, such as for a fracture of the radial bone, the patient's thumb may prevent suitable alignment of the steel rod and the articulation. This problem has been addressed to a certain extent with ring external fixators, such as Ilazarov. However, such fixators necessitate a number of invasive pin placements and lead to a very big and cumbersome fixator.
Also known are casts that rely on a chemical reaction to change from a bandage (flexible) to cast (rigid) form in a reaction is irreversible. In contrast, the present invention provides a non-chemical, mechanical solution as the device provided can be adjusted from being flexible to being rigid in a reversible fashion.
It is an object of the present invention to obviate or alleviate these and other disadvantages of conventional fixators. It is a further object of the invention to provide a non-invasive external fixator, which permits movement of a joint near the fracture site and also allows for fracture reduction and aids fracture manipulation. The invention also provides a connecting device for the fixator of the invention. Connecting devices in the art are used to fix a rod or cylinder, i.e. a circular surface. Furthermore, the invention relates to a hinge suitable for use with a fixator. Hinges have been used in medical devices. However, these hinges have limitations to be used in fracture fixation device. These have traditionally been made of radiopaque materials such as metals and hence obscure the area of interest in fractures in radiographs (X-rays), see for example EP0676941 and EP0879032. It is very difficult to assess the centre of rotation of these hinges on radiographs and to ascertain whether these are in the plane of the joint motion. The present invention is aimed at addressing the shortcomings in the field.